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ENV510 Landscape Ecology and GIS
Definitions
& descriptions | Structure
& pattern | Function
& process | Change
& dynamics | Management
implications
Importance
| Processes | Instigators
| Disturbance |
Spatial Causes
| Attributes
| Clearance
| Fragmentation
| Variegation
Need
for a new model
Variegated
landscapes
Rangelands
variegation
The fragmentation
model applies to the Kellerberrin study area and many cultural landscapes in
Europe and North America where it was originally developed, however it may not
be applicable to landscape transformation in all areas (McIntyre
and Barrett, 1992), especially grassy landscapes.
The concept of fragmentation implies remnants are isolated by areas that are hostile to the organisms within the remnants so species that persist in this sort of landscape need to rely on corridors or long distance dispersal to move between patches. This may be the case in the wheatbelt of WA, but in the New England tablelands of NSW, land transformation has taken place in a different way. This may have caused you some difficulty with the fragmentation activity.
Variegated
landscapes are described as being 'where native vegetation still forms the matrix
but has been modified in a variable way' (McIntyre,
1994).
A
variegated landscape approach is very relevant to understanding the effects
of disturbance in rangelands and forestry land use types throughout Australia.
More?
If you are interested in this area you might like to read the McIntyre and Barrett article "Habitat Variegation: An alternative to fragmentation".
Rangelands
can be described as being variegated because native vegetation makes up the
matrix but the native vegetation has been modified in some way.
This
means that remnant vegetation exists in a 'sea' of native vegetation that is
modified to different extents but not totally removed. So, in this model of
the landscape, modifications are represented as a gradient of change rather
than discrete sharp boundaries as the fragmentation model suggests. Continuous
variation across the landscape exists in locations that have undergone this
form of transformation.
The
implications of this type of transformation for ecosystem flows and processes
will be different from those found in a fragmented and relictual
landscape.
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